The present invention pertains to dilation catheters of the so-called rapid exchange type with an inflatable balloon and with a lumen for a guide thread.
These catheters can be used in various operating and surgical procedures and/or for inserting molds, called stents, inside the ducts or lumens of a live body.
A dilation catheter generally comprises a thin and extended tubular element and usually has an inflatable balloon near its distal end, a first lumen for a guide thread and at least a second lumen for the passage of a fluid for inflating the balloon.
In the prior-art designs, the first and the second lumina of the catheter may be coaxial or not, may be made into a single extruded element, separated by a baffle, or formed by two small tubes of different diameter arranged one inside the other.
However, the current trend is to create a point for passing the guide thread in the catheter in a zone close to the distal end even though before, above, the inflatable balloon in order to reduce or preferably balance the sliding force of the catheter along the guide thread during the insertion in the body.
Various embodiments of dilation catheters have already been proposed in order to meet such a requirement.
In one embodiment, the catheter has a single extruded body, which has two integral lumina (e.g., EP-A-0 712 639) with one lumen for inflating the balloon and another lumen for the guide thread, this second lumen simply having a radial opening for the passage of the guide thread above the balloon.
According to another embodiment, a first and a second lumen of the catheter (e.g., U.S. Pat. No. 5,102,403) are obtained, in a distal section from the front of the balloon of the catheter, by means of a longitudinal deformation of a starting tube which has a single lumen. The deformation is performed along a generating line of the tube and aimed at creating a lumen for the guide thread, which lumen has an opening on one side of the starting tube, which goes deep down to more or less on the axis of the tube, and which opens at the distal end of same, while the lumen proper of the starting tube opens into the balloon.
Starting from these premises the primary object of the present invention is to provide a novel dilation catheter structure produced by means of an original configuration and combination of single tubular elements, therefore not in a single piece obtained from extrusion or deformed as taught by the prior art.
According to the invention, a dilation catheter structure of the rapid exchange type is provided with an inflatable balloon and with a lumen for a guide thread (i.e., the connection strand, filament etc). The structure has a main tube, which has a distal end, a distal tube and a guide tube, in which the guide tube extends in the distal tube. The proximal ends of the guide tube and the distal tube are joined to one another and at the distal end of the main tube. The proximal end of the guide tube has an opening on one side of the main tube. The proximal end of the distal tube encloses the distal end of the main tube and the proximal end of the guide tube tightly and simultaneously.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which a preferred embodiment of the invention is illustrated.